Electric circuit breaker



Jan. 12, 1932. PEARCE ELECTRIC CIRCUIT BREAKER Filed June 4, 1951 Inventor: Herbert Pearce,

His Atto -negg Patented Jan. 12, 1932 UNITED STATES PATENT oar-Ice HERBERT PEARCE, OF ALTRINOEAM, ENGLAND, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK ELECTRIC CIRCUIT BREAKER Application filed June 4, 1931, Serial No. 542,129,:11111 in Great Britain June 24, 1980.

My invention relates to electric circuit breakers, more particularly to fluid-break switches of the explosion-chamber type.

\ A principal object of my invention is the provision of an improved electric circuit breaker of the explosion-chamber type having an auxiliary or pressure generating break for extinguishing by a blast of insulating liquid the main arc formed during opening movement of the breaker.

My invention will be more fully set forth in the following description referring to the accompanying drawings, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification. f

Referring to the drawings, Fig. 1 is an elevational view, partly in section, of circuit breaker structure embodying my invention in the closed circuit position, and Fig. 2 is a similar partial view showing the movable contact structure in the open circuit position.

The circuit breaker structure illustrated in Fig. 1 comprises generally an explosion chamber 1 and contact structure 2 movable within the explosion chamber to engage a stationary contact 3 mounted at one end thereof. For

the purpose of simplicity in description and illustration, the conventional circuit breaker ber 1 is formed by a. strong insulating cylinder 4 provided with a lower end wall 5 secured in any suitable manner, as by the bolts 6, to the cylinder 4, the stationary contact 3 being mounted at the opposite end of the exlosion chamber and provided with an exaust opening or passage 7 communicating with the chamber 1. The contact 3 formed of suitable ,conductingmaterial is rigidly secured to the cylinder 4;, as by the bolts 8, insulatedas at 9, the'entire structure being in turn supported by the conductor stud 10 secured, as by screw threaded engagement, to the contact 3. The conductor stud 10 may be mounted in a well-known manner upon the corresponding main lead-in insulating bushing (not shown extending through the cover of the circuit reaker tank.

The movable contact structure 2 includes a rod 11 connected to the bridging member 12 and extending within the explosion chamber through an opening 13 in the end wall 5. Mounted for relative movement with respect to the rod 11 is a contact member 14 arranged to engage the stationary contact 3 adjacent the exhaust opening 7, so as to normally close the opening, for exam 1e, and to be in engagement in the close circuit position, as will be hereinafter described,

with the rod 11 thereby completing the circuit through the switch.

For the purpose of mounting the contact member 14 for relative movement with respect to the rod '11, there is provided structure comprising an insulating plate 15 suitably mounted on and carried by an enlarged contact portion 16 of the rod 11. The contact member 14 has likewise secured thereto a similar insulating plate 17, the plates 15 and 17 bein biased in a direction away from each other y a pair of compression springs 18 and 19,'the springs being suitably positioned and guided by rods 20 and 21 respectively, each secured to the plate 17 and freely slidable through openings in the plate 15. The springs 18 and 19 are furthermore surrounded by insulating-tubes 22 and 23 respec tively for the pur ose of preventing arcing to the springs. ovement of the insulating plates 15 and 17 away from each other is lim ited by stop members, as lock nuts 24* and 25 atthe -lower iends of the rods 20 and 21 respectively.

When the oil or other insulating liquid within the circuit breaker is at its proper level, as generally indicated in Fig. 1, the explosion chamber is entirely filled with oil and the exhaust opening 7 is but a short distance below the oil level so that the hydraulic 100 head at that point is substantially at a minimum.

Assuming now that the circuit is to be interrupted, the bridging member is released in a well-knownmanner to descend, causing downward movement of the rod 11 within the explosion chamber. By reason of the compression springs 18 and 19, the contact member 14 is maintained in engagement with the stationary contact 3 during the initial downward movement of the rod 11, this initial movement producing a pressure generating break between the lower butt contact surface of the contact member 14 and the coacting contact surface of the enlarged portion 16 of the rod 11. I As is well known, the initial are formed at the contact member 14 generates an'explosive pressure in the insulating liquid within the explosion chamber so that this pressure is efl'ectiveio force insulating liquid at high velocity through the exhaust opening 7 when the contact member 14 separates from the stationary contact 3. It will be apparent that the stop members 24 and 25 may be suitably adjusted to regulate the length of the initial pressure generating break and therefore, to a certain extent, the pressure generated.

As the downward movement of the rod 11 continues the plate 15 engages the stop members 24 and 25 carrying the contact member 14 downwardly so that the entire contact structure 2 moves as a unit to the final open circuit position illustrated in Fig. 2.

Due to the eneration of pressure within the explosion c amber prior to separation of the contact member 14 from the coacting contact 3, the main are formed at the fixed contact 3 is immediately radially traversed by the blast of oil in exhausting throu h the opening 7. This action is further faci itated by reason of the low hydraulic head at the exhaust opening, the space above the oil level being usually at atmospheric pressure.

The oil blast is particularly efi'ective to extinguish the arc-as liquid dielectric is interosed at a high rate between the arcing suraces and in such a manner that the arc is unable to dodge or shift with respect to the oil. Interruption of the current therefore generally occurs when the zero' part of the cycle has been reached.

After the circuit opening operation, fresh oil is free to refill the explosion chamber through the opening 7. The circuit closing movement is rformed in a well'known manner by elevating the bridging member 12, the rod 11 carrying the contact structure upwardly within the explosion chamber until the contact member 14 has engaged the stationary contact 3 and the contact portion 16 of the rod 11 has subsequently engaged the contact member 14, compressing the springs 18 and 19. It will therefore be noted that the circuit ismade at the buttcontact suropening 7 is designed so that the oil blast is directed away from the conductor stud 10, it being obvious that the position and shape of the exhaust may vary to suit the particular operating requirements.

It should be further understood that my invention is not limited tospecific details of construction and arrangement thereof herein illustrated, and that changes and modifications may occur to one skilled in the art without departing from the spirit of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric circuit breaker of the explosion-chamber type comprising a stationary contact at one end of the explosion chamber, said contact provided with an exhaust opening, and contact structure movable within said explosion chamber arranged to engage said stationary contact adjacent said exhaust opening, said movable contact structure fbrming during ,circuit opening movement a pressure generating break prior to separation of said contact structure from said stationary contact so that extinguishing liquid is forced at high velocity across the are subsequently formed at the stationary contact and through said exhaust opening;

2. An electric circuit breaker comprising an explosion chamber immersed in an insulating liquid, a stationary contact positioned at the upper end of said explosion chamber, said contact provided with an exhaust opening a short distance below the level of the insulating liquid, and contact structure movable within said explosion chamber arranged to engage said stationary contact adjacent said exhaust opening in the closed circuit position, said movable structure including means forming an initial pressure generating break in response to circuit opening movement prior to separation of the movable .contact structure from the stationary contact an explosion chamber immersed in insulating liquid, a stationary'contact provided with an exhaust opening mounted within said chamber, and movable contact structure coacting with said stationary contact including a rod extending within said chamber, and'a relatively movable contact member carried by said rod, said rod in the closed circuit (position engaging said contact memher an maintaining the same in engagement with said stationary contact atsaid exhaust opening, circuit opening movement of said rod forming an initial pressure generating break between said rod and contact member causing exhaust of insulating liquid at high velocity across the are formed at said stationary contact.

4. An electric circuit breaker comprising an explosion chamber immersed in an insulating liquid, a stationary contact provided with an exhaust opening mounted at one end of said chamber, and contact structure movable within said explosion chamber to engage said stationary contact adjacent said exhaust opening, said movable structure including a rod extending through the opposite end of said chamber, insulating structure carried by said rod, and a contact member mounted upon said insulating structure and resiliently biased in a direction away from said rod, circuit closing movement of said rod causing engagement of said contact member with said stationary contact and subsequent engagement of said rod and contact member, circuit opening movement forming an initial pressure generating break between-said rod and contact member causing exhaust of insulating liquid at high velocity across the are subsequently formed at the stationary contact.

5. An electric circuit breaker comprising an explosion chamber immersed in oil, a stationary contact forming an exhaust passage communicating with said chamber, and contact structure movable within said chamber to engage said stationary contact at said exhaust passage, said contact structure including a relatively movable contact member arranged to form an initial pressure generating break in response to circuit opening movement at a point spaced from said stationary contact, the pressure generated within said chamber causing exhaust of oil at high velocity across the main arc subsequently formed at said stationary contact.

In witness whereof, I have hereunto set HERBERT PEARCE.

' my hand. 

